There has been known an EGR (Exhaust Gas Recirculation) system in which a part of exhaust gas flowing through an exhaust passage is returned from an air intake passage into a combustion chamber to reduce a combustion temperature of an air-fuel mixture in the chamber, and thereby a percentage of nitrogen oxide in the exhaust gas is reduced. In this EGR system, an EGR control valve capable of opening and closing an EGR passage is interposed in the middle of this EGR passage whose both ends are communicated with the air intake passage and the exhaust passage respectively, and exhaust gas is recirculated to an air intake passage side in a predetermined operating range of the engine.
In recent years, there has been a significant growing social need for purifying exhaust gas, and from such a viewpoint, has also been promoted so-called idle stop control in which actuation of the engine is stopped when a vehicle is stopped, and in which useless emission of carbon dioxide is prevented, and at the same time, useless consumption of fuel is suppressed. However, since effective exhaust gas is not interposed in the EGR passage at the time of restart of the engine in such idle stop control, it is difficult to have exhaust gas contained in an intake air supplied to the combustion chamber with fuel particularly at the beginning of start.
A technology to solve such problem has been proposed in Patent Literature 1. Namely, in idle stop control, the technology is configured such that EGR gas can be temporarily stored in an EGR passage at the time of stop of an internal combustion engine, and that the EGR gas can be supplied particularly to a first explosion cylinder in which fuel supplied first burns in addition to an intake air at the time of restart of the engine.